1. Technical Field of the Invention
The present invention relates to semiconductor insulation structures for cooling semiconductor modules incorporating semiconductor elements and, more particularly, to a semiconductor insulation structure for a semiconductor module, incorporating a semiconductor module herein, an insulation member and an electrically conductive structural body all of which are held in pressured contact with each other
2. Description of the Related Art
In the related art, attempt has heretofore been made to provide a semiconductor insulation structure such as a structure shown in FIGS. 22 and 23 (see Japanese Patent Laid-Open Publication No. 2001-320005, US2005/0040515A1 and US012006/1020047A1). With such a structure, radiator plates 950, 950 sandwich a semiconductor element 91, incorporated in a semiconductor module 9, and coolers 7, 7 are mounted on the radiator plates 950, 950, respectively, with the semiconductor element 9, the radiator plates 8, 8 and the coolers 7, 7 being held in pressured contact with each other for cooling the semiconductor module 9. The semiconductor module 9 further includes insulation members 8 each composed of ceramic material and interposed between the cooler 7 and the radiator plate 950, exposed to a surface of the semiconductor module 9, to ensure electrically insulating property therebetween.
However, under circumstances where the radiator plates 950, 950 are made of copper and the coolers 7, 7 are made of aluminum, if the coolers 7, 7 and the radiator plates 950, 950 are pressurized against each other with the intervening insulation members 8, 8, the coolers 7, 7 are liable to deform with greater extents than those of the radiator plates 950, 950 when applied with a given rate of load. When this takes place, bending forces act on the insulation members 8, 8 to cause the deformations thereof due to the deformations of the coolers 7, 7. This result in the occurrence of fears for the insulation members 8, 8 to undergo crack or damages. Thus, difficulties are encountered in ensuring electrically insulating property between the semiconductor module 9 and the coolers 7, 7.
With such a structure, when the radiator plate 950, having a less deformation rate in terms of a given load, is brought into abutting engagement with a surface of each cooler 7 that has a high deformation rate in terms of the given load, stress concentration occurs on an abutment portion between the radiator plate 950 and the cooler 7. When this takes place, the cooler 7 deforms in the abutment portion at an area in the vicinity of an outer circumferential periphery 951 of the radiator plate 950. That is, under the circumstances where the radiator plates 950, 950 have the less deformation rates in terms of the given load than those of the coolers 7, 7, the presence of the outer circumferential periphery 951 remaining inward of an outer circumferential periphery 751 of the cooler 7 tends to cause the cooler to deform in a manner mentioned above. Thus, deterioration occurs in electrically insulating property between the semiconductor module 9 and the cooler 7.